Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/20—Controlling the colour of the light
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/20—Controlling the colour of the light
  • H05B45/22—Controlling the colour of the light using optical feedback
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/20—Controlling the colour of the light
  • H05B45/28—Controlling the colour of the light using temperature feedback
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
  • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Definitions

• An optoelectronic device for emitting a mixed light is specified.
• LEDs emitting different colors and / or a plurality of phosphors are usually used with the use of light-emitting diodes (LEDs).
• LEDs light-emitting diodes
• to produce white light it is possible to superimpose spectral components in the yellow-green and red-wavelength ranges which are emitted by different LEDs.
• the stabilization of the color locus of the mixed light is challenging compared to the temperature. This is due, for example, to different temperature dependencies of the chip technologies involved.
• the LED chips can lead to a change in the color locus and / or the intensity of the mixed light.
• the control and regulation to any color location is usually possible only using at least three different LEDs, such as for the production of white Mixed light through a yellow-green, a red and additionally a blue emitting LED.
• the perception of light by a viewer continues to be known to depend on the sensitivity of the human eye as a function of the perceived wavelength.
• the average spectral sensitivity of the human eye in the average color normal-view observer is represented by the known so-called V ⁇ curve, in FIG. 1A the spectral sensitivity R of the human eye in arbitrary units as a function of the wavelength ⁇ in a wavelength range of 400 to 700 Nanometer shows.
• V ⁇ curve 990 in FIG. 1A shows that light stimuli which are caused by equally strong light fluxes with different wavelengths lead to different brightness impressions. This effect can have a significant influence on the color and light impression of the perceived mixed light, especially in mixed light sources with LEDs, if one or more LEDs have, for example, a temperature-dependent and / or age-related wavelength shift of the emitted light.
• At least one object of certain embodiments is to specify an optoelectronic device for emitting light with a first and a second semiconductor light source.
• a first semiconductor light source having a first light emitting diode (LED) which, when a first current is applied, emits light having a first characteristic wavelength in the first wavelength range and at a first intensity
• a second semiconductor light source having a second LED emitting, upon application of a second current, light having a second characteristic wavelength in the second wavelength range and at a second intensity, the first and second wavelength ranges having different wavelength-dependent intensity distributions from each other,
• an optical sensor for converting a part of the light emitted by the first semiconductor light source into a first sensor signal and a part of the light emitted by the second semiconductor light source into a second sensor signal
• a control device for controlling the first and second current in response to the first and second
• the first characteristic wavelength and the first intensity of the light emitted by the first semiconductor light source have a first temperature dependence and / or current dependence and / or aging and
• the second characteristic wavelength and the second intensity of the second semiconductor light source radiated light have a second temperature dependence and / or current dependence and / or aging, which is different from the first temperature dependence, - the optical sensor in the first wavelength range has a first wavelength-dependent sensitivity and in the second wavelength range has a second wavelength-dependent sensitivity to the first and second Temperature dependence and / or current dependence and / or aging are adapted, and - the control device controls the first and second current such that the first sensor signal to the second sensor signal has a predetermined ratio.
• light may refer in particular to electromagnetic radiation having one or more wavelengths or ranges of wavelengths from an ultraviolet to infrared spectral region.
• light may be visible light and include wavelengths or wavelength ranges from a visible spectral range between about 350 nm and about 800 nm.
• Visible light can be characterized here and below, for example, by its color locus with x and y color coordinates in accordance with the so-called CIE 1931 color chart or CIE standard color chart known to a person skilled in the art.
• white light or light with a white luminous or color impression here and below light with a color locus corresponding to the color locus of a blackbody radiator can be referred to, or by less than 0.1 and preferably less than 0.05 in x and or y color coordinates deviates from the color locus of a black plank body radiator.
• white luminous impression caused luminous impression by light which has a color rendering index (CRI) known by a person of greater than or equal to 60, preferably greater than or equal to 70 and more preferably greater than or equal to 80.
• CRI color rendering index
• a luminous impression may be designated, which has a color temperature of less than or equal to 5500 K.
• cool white here and below may be designated a white luminous impression having a color temperature of greater than 5500 K.
• color temperature may here and below designate the color temperature of a blackbody planckers or else the so-called correlated color temperature (CCT) known to the person skilled in the art in the case of a white luminous impression in the sense described above, which are characterized by chromaticity coordinates may deviate from the chromaticity coordinates of the Planck blackbody radiators.
• CCT correlated color temperature
• a first and a second luminous impression can be referred to here and below as “different” if the first luminous impression is caused by light having a first color locus and the second luminous impression by light having a second color locus and the first color locus is perceivable as different from the second color locus
• different light impressions can be caused by first and second wavelength ranges which are different from one another
• Wavelength range accordingly be designated as different, if the first and second wavelength range of a mutually different spectral
• the first wavelength range has at least one spectral component that is not contained in the second wavelength range, it should be emphasized that a first and a second frequency range are the same
• Wavelength range which are different from each other, may well have the same spectral components.
• the first and second wavelength ranges in one, several or all of the spectral components may coincide with respect to their wavelength as long as at least one of the two wavelength ranges has at least one spectral component that is not or not at the same relative intensity in the other wavelength range, so that the first and second wavelength ranges cause respective luminance and color impressions with different x and / or different y coordinates in the CIE standard color chart.
• This may mean, in particular, that the first and second wavelength ranges, for example at the same wavelength, each have a spectral component which differs in intensity, for example by a factor of greater than or equal to 10.
• a first and second color location or luminous impression are referred to as being perceivable differently from one another, if they are perceivable by an average human observer as being different from one another.
• a first and second luminous impression with a first and second color location are not different in the sense of the present application, if the second color locus in the MacAdams ellipse with the first color locus as the center or reference Farbort lies or vice versa.
• the concept of MacAdams ellipses in terms of Perceptibilities of color differences is known to the person skilled in the art and will not be discussed further here.
• the first or second characteristic wavelength may denote the highest intensity wavelength of the first or second wavelength range.
• the first and second characteristic wavelengths may also denote the mean wavelength of the first and second wavelength ranges, respectively.
• the first or second characteristic wavelength can also denote the respective weighted average wavelength of the first and second wavelength range over the individual spectral intensities.
• a change of the first or second characteristic wavelength results from a shift of the first or second wavelength range and / or from a change in the relative intensities of the spectral portions of the first and the second wavelength range.
• a change in the first or second characteristic wavelength thus also results in a change of the respective color locus of the light emitted by the first or second semiconductor light source.
• the first sensor signal is dependent on the first intensity as well as on the first wavelength range or the first characteristic wavelength.
• the first sensor signal changes when the first intensity changes and / or when the first wavelength range or the first characteristic wavelength changes, even if the first sensor signal changes Intensity remains the same.
• the first sensitivity can increase or decrease with increasing wavelength in the first wavelength range, so that the first sensor signal can increase or decrease correspondingly with increasing first characteristic wavelength, even if the first intensity remains the same. Accordingly, what is said in connection with the first sensor signal and the first sensitivity also applies to the second sensor signal and the second sensitivity.
• the optical sensor can have a wavelength-dependent sensitivity, at least in the first and second wavelength ranges, which is different in magnitude, as described above for the sensitivity of the human eye for different wavelengths.
• the first and second sensor signal can therefore also take into account changes in the first or second characteristic wavelength in addition to the change in the first or second intensity.
• the control and control task of the optoelectronic device which is particularly preferred to lead to a constant possible light and color impression of the mixed light, better than in known control devices can be solved , Since the optical sensor thus has the first and second sensitivity, which are adapted to the first and second temperature dependence and / or current dependence and / or aging, are contained by the optical sensor, the necessary information for correction signals for the first and second streams, by means of which For example, the color location and / or the intensity of the Msichlichts can be regulated. The predetermined ratio of the first and second sensor signals to each other can be kept constant by the control device.
• the control device thus thus makes it possible, for example, for the ratio of the first sensor signal to the second sensor signal to remain constant, for example, when the ambient and / or operating temperature changes. This means, in particular, that when the first sensor signal and / or the second sensor signal changes, the ratio of the first to the second sensor signal would also change
• the predetermined ratio of the first to the second sensor signal may also depend on the strength of the first and / or second sensor signal, so that the predetermined ratio may change in a predetermined manner in dependence on the first and / or second sensor signal. As a result, it may be possible, for example, to regulate the color location of the mixed light with regard to temperature, current application and / or aging of the light-emitting diodes together with the first and second sensitivity.
• control devices in which the intensity emitted, for example, by a plurality of LEDs is measured with photodiodes, usually only the intensity changes of the emitted light are taken into account.
• Conventional control devices thus determine a correction signal which alone is dependent on the respectively measured intensity.
• the known control devices but no wavelength shifts of the emitted light compensate.
• even such wavelength shifts despite the radiated intensity kept constant by the regulating device, can lead to a change in the perceived color and light impression due to the wavelength-dependent sensitivity of the human eye, since a luminous flux kept constant as a function of the wavelength becomes weaker or weaker is perceived more strongly.
• a control device having one or more temperature sensors.
• a table or a database is further stored, from which correction values for the control of the LEDs can be read in dependence on the temperature.
• correction values for the control of the LEDs can be read in dependence on the temperature.
• the respective temperature-dependent wavelength shifts can also be taken into account in the correction values.
• the regulating device of the optoelectronic device described here can comprise passive and / or active analog and / or digital electronic components, purely for example controllable resistors, fixed resistors, capacitors, coils, transistors, Operational amplifiers, microcontrollers, microprocessors and combinations thereof.
• controllable resistors purely for example controllable resistors, fixed resistors, capacitors, coils, transistors, Operational amplifiers, microcontrollers, microprocessors and combinations thereof.
• Control device may be formed as a feedback loop or be designed directly as a power source for the first and second semiconductor light source or integrated into such a power source.
• the control device may comprise electronic components and circuits, which are known from regulators for proportional control, integrating control and / or differential control and which are suitable, one or more signals, in particular the first and second sensor signal, relative to predetermined so-called actual values or also in particular to regulate and control relative to one another. Due to the sensor described here, components which are required in the known control devices described above for balancing measured values with stored table values can be dispensed with in the control device.
• An LED of a semiconductor light source that is about the first and / or the second LED, can in particular a
• Epitaxial layer sequence ie an epitaxially grown semiconductor layer sequence.
• the LED can be designed, for example, on the basis of InGaAlN.
• InGaAlN-based LEDs and semiconductor layer sequences include, in particular, those in which the epitaxially produced semiconductor layer sequence generally has a layer sequence of different individual layers which contains at least one single layer comprising a material from the III-V compound semiconductor material system In x Al y Ga x - y N with O ⁇ x ⁇ l, O ⁇ y ⁇ l and x + y ⁇ 1.
• Semiconductor layer sequences comprising at least one InGaAlN-based active layer can be used, for example preferably emit electromagnetic radiation in an ultraviolet to green wavelength range.
• the LED can also be based on InGaAlP, that is, the LEDs are different
• Compound semiconductor material system In x Al y Gai x - y P with 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1 and x + y ⁇ 1 has.
• Semiconductor layer sequences or LEDs which have at least one active layer based on InGaAlP, for example, can preferably emit electromagnetic radiation with one or more spectral components in a green to red wavelength range.
• III-V compound semiconductor material systems such as an AlGaAs-based material or a II-VI compound semiconductor material systems.
• an LED comprising an AlGaAs-based material may be capable of emitting electromagnetic radiation with one or more spectral components in a red to infrared wavelength range.
• An II-VI compound semiconductor material may include at least one element of the second main group or the second subgroup such as Be, Mg, Ca, Sr, Cd, Zn, Sn, and a sixth main group element such as O, S, Se , Te.
• an II-VI compound semiconductor material comprises a binary, ternary or quaternary compound comprising at least one element of the second main group or second subgroup and at least one element of the sixth main group.
• binary, ternary or quaternary compound may, for example, have one or more dopants and additional constituents.
• the II-VI compound semiconductor materials include: ZnO, ZnMgO, CdS, ZnCdS, MgBeO.
• the semiconductor layer sequence of the first and / or the second LED may further comprise a substrate on which the above-mentioned III-V or II-VI compound semiconductor materials are deposited.
• the substrate may be one
• semiconductor material for example, an above-mentioned compound semiconductor material system include.
• the substrate may include or may be sapphire, GaAs, GaP, GaN, InP, SiC, Si, and / or Ge.
• the semiconductor layer sequence can have as active region, for example, a conventional pn junction, a double heterostructure, a single quantum well structure (SQW structure) or a multiple quantum well structure (MQW structure).
• the term quantum well structure includes in particular any structure in which charge carriers can undergo quantization of their energy states by confinement.
• the term quantum well structure does not specify the dimensionality of the quantization. It thus includes quantum wells, quantum wires and quantum dots and any combination of these structures.
• the semiconductor layer sequence can comprise further functional layers and functional regions, for example p- or n-doped charge carrier transport layers, ie electron or
• Hole transport layers Undoped or p- or n-doped confinement, cladding or waveguide layers, barrier layers, planarization layers, buffer layers, Protective layers and / or electrodes and combinations thereof.
• Such structures relating to the active region or the further functional layers and regions are known to the person skilled in the art, in particular with regard to construction, function and structure, and are therefore not explained in more detail here.
• the first and / or the second LED can, for example, also be designed as thin-film light-emitting diode chips.
• a thin-film light-emitting diode chip is characterized in particular by one or more of the following characteristic features: on a first side facing a carrier element
• Main surface of a radiation-generating epitaxial layer sequence is applied or formed a reflective layer which forms at least a portion of the electromagnetic generated in the epitaxial layer sequence
• the epitaxial layer sequence has a thickness in the range of 20 ⁇ m or less, in particular in the range of 10 ⁇ m; and / or the epitaxial layer sequence contains at least one
• the epitaxial layer sequence of a thin-film light-emitting diode chip can, after being grown on a growth substrate, be re-bonded to a carrier element
• the first and / or the second semiconductor light source and thus the at least one first and / or second LED can create a mixed-color and in particular, for example, a white luminous impression.
• the first and / or second LED one
• the wavelength conversion substance may be suitable for converting at least part of the light emitted by an LED, which may be in an ultraviolet to blue spectral range, into longer wavelength light, ie into light with one or more spectral components in a green and / or one yellow and / or a red wavelength range.
• a mixed-color, for example white, light impression can be generated.
• the wavelength conversion substance may comprise one or more of rare earth and alkaline earth metal garnets such as YAGiCe 3+ , nitrides, nitridosilicates, sions, sialons, aluminates, oxides, halophosphates, orthosilicates, sulfides, vanadates, perylenes, coumarin and chlorosilicates. Furthermore, the rare earth and alkaline earth metal garnets such as YAGiCe 3+ , nitrides, nitridosilicates, sions, sialons, aluminates, oxides, halophosphates, orthosilicates, sulfides, vanadates, perylenes, coumarin and chlorosilicates. Furthermore, the rare earth and alkaline earth metal garnets such as YAGiCe 3+ , nitrides, nitridosilicates, sions, sialons, aluminates
• Wavelength conversion substance also suitable mixtures and / or combinations thereof.
• the wavelength conversion substance can be embedded in a transparent matrix material which surrounds or contains the wavelength conversion substance.
• the transparent matrix material may, for example, silicones, epoxides, acrylates, imides, carbonates, olefins or derivatives thereof in the form of monomers, oligomers or polymers as Have mixtures, copolymers or compounds with it.
• the matrix material may be an epoxy resin, polymethylmethacrylate (PMMA) or a silicone resin.
• the first semiconductor light source can have a white luminous impression in combination with a
• the first semiconductor light source can have a first LED based on InGaN, which emits light in a blue wavelength range.
• the first LED can have a wavelength conversion substance which converts part of the blue primary light into green, yellow or yellow-green secondary light, so that the first wavelength range comprises blue and green, yellow or yellow-green spectral components and gives a greenish-white to cold-white color impression .
• the second semiconductor light source may comprise a second LED based on InGaAlP, which emits light in a second, red wavelength range.
• the second semiconductor light source may also comprise a second LED based on InGaAlP, which
• the optoelectronic device Produces light in a second, yellow wavelength range, so that the optoelectronic device can emit a mixed light with a cold white light impression.
• Such optoelectronic devices may be possible for a rough pre-selection of the desired color location at a given ambient and operating temperature by the first semiconductor light source, while a fine adjustment or fine tuning of the color locus is possible by the second semiconductor light source Alternatively, the first and second semiconductor light source may be reversed with respect to the previously described wavelength ranges and color impressions.
• first semiconductor light source and / or the second semiconductor light source each have a plurality of first and second LEDs, which are each made the same.
• Light emitting diodes typically have a negative temperature dependence of the radiated intensity in typical ambient and operating temperatures in the range from -40 0 C to 125 ° C. This means that the intensity of the radiated light decreases with constant electrical current with increasing ambient and operating temperature. Depending on the design and choice of material of an LED, the intensity of the emitted light from an LED of 100% at a temperature of 0 0 C to an intensity of less than or equal to 90% to greater than or equal to 10% at a
• LEDs can have a temperature-dependent shift of the characteristic wavelength of up to +/- 5% or more, that is to say of a few nanometers, in a temperature range from 0 ° C. to 100 ° C.
• the optical sensor for measuring the first and second intensity or a respective part thereof may in particular comprise or be a photodiode and particularly preferably a silicon-based photodiode. Silicon-based photodiodes can vary depending on
• Embodiment by high or at least sufficient intrinsic sensitivity over the entire wavelength range of visible light distinguished.
• the spectral sensitivity in the range of about 300 to about 1000 nanometers increases continuously and then drops again, depending on the design, the maximum sensitivity may also be in the range of about 550 to less than 1000 nanometers.
• the latter may comprise a photoactive material having the first and / or second sensitivity as intrinsic intensity or alternatively or additionally an optical filter.
• the optical filter may have a wavelength-dependent transmittance for adjusting the first and / or second sensitivity.
• the optical filter in the first and / or second wavelength range can have a transmission for the light of the first or second semiconductor light source, which, in combination with the intrinsic sensitivity of the optical sensor material, corresponds to the desired first or second sensitivity.
• This may in particular also mean that the combination of the optical filter with its wavelength-dependent transmittance together with the intrinsic sensitivity of the optical sensor material, that is about silicon, the desired first and second sensitivity results.
• the optical filter may comprise or be embodied as an absorptive and / or a thin-film filter which leads to the desired first and / or second sensitivity in the first and / or second wavelength range together with the intrinsic spectral sensitivity of the optical sensor.
• the optical sensor may, for example, also have a first sensor facet and a second sensor facet. The part of the radiated from the first semiconductor light source
• Light in the first wavelength range can be radiated at least on the first sensor facet, while the part of the light emitted by the second semiconductor light source in the second wavelength range can be irradiated at least on the second sensor facet.
• an optical filter can also be arranged on the first and / or the second sensor facet, so that the optical sensor together with the optical filter in the region of the first sensor facet has the first sensitivity in the first wavelength range and the second sensitivity in the region of the second sensor facet second wavelength range.
• the light of the first semiconductor light source and the light of the second semiconductor light source can also be irradiated onto the entire active surface of the optical sensor when the optical filter, for example, the light in the second
• Wavelength range can discriminate against the entire spectrum with the first and second wavelength range or against the light in the first wavelength range in the region of the second sensor facet.
• Sensor facets can be electrically and optically separated from each other, so that the optical sensor directly the first sensor signal as a signal of the first sensor facet and the second sensor signal can deliver as a signal of the second sensor facet.
• the optical sensor may also comprise two separate photodiodes.
• the first and / or the second current can be modulated in the operation of the optoelectronic device.
• the control device may be suitable in this case to divide the signal of the optical sensor by means of frequency analysis, for example by means of known frequency mixing and filtering methods, in the first and second sensor signal.
• the first and the second current can be modulated with different frequencies or only one of the two currents.
• the first and / or the second current can be amplitude modulated by switching on and off, for example in the form of a square wave signal.
• the optical sensor in the form of a spectral analysis by means of the optical filter and / or a frequency analysis with modulated first and / or second current, it may be possible for the optical sensor to "differentiate" between the light of the first semiconductor light source and the light of the second semiconductor light source As a result, the optical sensor itself can transmit the light of the first semiconductor light source and the light of the second
• the mixed light is as small as possible in terms of its color locus
• the second characteristic wavelength can be in the region of the falling edge of the V ⁇ curve.
• the first characteristic wavelength may be, for example, in a blue to green wavelength range, so that the mixed light of the optoelectronic device can impart a white light impression.
• the first characteristic wavelength for example, on the rising edge or the maximum of the V ⁇ curve in the range between about 400 to 550 nanometers.
• the second characteristic wavelength in the region of the falling edge of the V ⁇ curve it would be obvious for the second characteristic wavelength in the region of the falling edge of the V ⁇ curve that the second sensitivity has the same wavelength-dependent slope as the V ⁇ curve in the second wavelength range
• the wavelength-dependent perception of the human eye could be compensated by such a sensitivity adapted to the V ⁇ curve. If, here and below, wavelength-dependent slopes of the V ⁇ curve and wavelength-dependent slopes of the first and second sensitivity are compared, then Unless stated otherwise, it is assumed that the respective spectral dependencies are normalized to a maximum value of 1.
• the average wavelength-dependent slope of the V ⁇ curve in the wavelength range between 600 and 650 nanometers is approximately -1% / nm.
• the ratio of the mean wavelength-dependent slope of the second sensitivity to the mean wavelength-dependent slope of the V ⁇ curve is less than 1 in the second wavelength range , In other words, this means that the second sensitivity decreases more slowly with increasing wavelength than the V ⁇ curve.
• the ratio of the mean wavelength-dependent slope of the second sensitivity to the mean wavelength-dependent slope of the V ⁇ curve in the second wavelength range may be less than or equal to 0.8 and greater than or equal to 0.2, and more preferably approximately 0.5.
• the optoelectronic device described here can be embodied in particular such that a mixed light can be emitted which is in a temperature range of greater than or equal to 0 ° C. and less than or equal to 60 ° C., preferably less than or equal to 100 ° C., and particularly preferably greater or equal to -40 0 C and less than or equal to 125 ° C has a temperature-dependent color locus shift about a mean color locus that extends along a major axis of a MacAdams ellipse around the center color locus.
• the color locus and the center locus can be characterized by a first color point of light emitted at a temperature of the optoelectronic device, for example, 0 0 C the mixed light and a second color point of light emitted at a temperature of for example 60 ° or 100 0 C the mixed light.
• the temperature-dependent color locus shift can then be characterized in a first approximation by the connecting line between the first and second color loci.
• “Along the major axis” in this context means that the geometric projection of this connecting line on the main axis of the MacAdams ellipse is longer than the projection of the connecting line on the minor axis of the same MacAdams ellipse parallel to or at least approximately parallel to the major axis of the associated MacAdams ellipse Color locus shifts that extend from the center or reference color location along the major axis of a MacAdams ellipse are more difficult to discern than those along the minor axis of the MacAdams ellipse with a numerically equal color coordinate difference.
• the optoelectronic device may comprise a housing or a printed circuit board in which or on which the first semiconductor light source, the second semiconductor light source and the optical sensor are arranged.
• the housing may comprise a plastic, in particular a thermoplastic or a thermosetting plastic.
• the housing may be replaced by a molding process such as transfer molding, injection molding, Forming, cutting, sawing, milling or a combination thereof can be produced.
• the plastic may have siloxane and / or epoxy groups and be formed as a silicone, epoxy or a hybrid material of a mixture or a copolymer of silicone and epoxy.
• the plastic may also include polymethyl methacrylate (PMMA), polyacrylate, polycarbonate and / or imide groups.
• the housing may for example have a recess in which at least the first semiconductor light source and the second
• Semiconductor light source is arranged and via which the light in the first wavelength range can be emitted.
• the optical sensor may also be arranged in the recess.
• the housing may further include a lead frame for electrically contacting the first semiconductor light source, the second semiconductor light source and the optical sensor.
• the lead frame may be integrated into the housing, wherein the lead frame is formed by the housing body, surrounded and / or surrounded by this.
• the lead frame may have one or more mounting areas on which or the first semiconductor light source, the second semiconductor light source and the optical sensor can be applied.
• the lead frame may have a plurality of electrical connection options for electrical contacting of the first semiconductor light source, the second semiconductor light source and the optical sensor, which are formed approximately as bond pads or as mounting surfaces.
• the mounting area or the mounting areas can in particular a suitable interconnection as well as an electrical connection of the first Semiconductor light source, the second semiconductor light source and optionally also the optical sensor to an external power and voltage supply and / or to the control device be possible.
• the mounting area may be formed, for example, as a mounting surface on the lead frame.
• the optoelectronic device can have a third semiconductor light source with at least one third light-emitting diode which, upon application of a third current during operation, has light with a third characteristic wavelength in a third light-emitting diode
• Wavelength range and radiates with a third intensity may be different from the first and second wavelength ranges.
• the third characteristic wavelength and the third intensity may have a third temperature dependence and / or current dependence and / or aging.
• a part of the light of the third semiconductor light source can be irradiated onto the optical sensor, which has a third wavelength-dependent sensitivity in the third wavelength range, which corresponds to the third
• the control device may regulate the first, second and third currents such that the ratio of two each of the first, second and third sensor signals has a predetermined ratio.
• the third semiconductor light source and the third LED may include one or more features or combinations thereof as described above in connection with the first and second semiconductor light sources and the first and second LEDs.
• the third sensitivity of the optical sensor can be made possible by the intrinsic sensitivity of the sensor itself in the third wavelength range or also by the combination of the optical sensor with an optical filter as described above.
• the optical sensor can also have a third sensor facet and / or further features mentioned above.
• FIG. 1A shows a schematic representation of the V ⁇ curve
• FIGS IB to 2 are schematic representations of the CIE
• FIGS. 3A and 3B are graphs of temperature dependencies of first and second LEDs according to an exemplary embodiment
• FIGS. 4A and 4B are schematic representations of an optoelectronic device according to another
• FIGS. 5A and 5B are schematic representations of optical sensors according to further exemplary embodiments.
• FIGS. 6A and 6B are schematic representations of
• FIGS. 7A to 1OB show schematic representations of sensitivities of optical sensors and the resulting temperature-dependent color location shifts of the mixed light of optoelectronic devices according to further embodiments and FIGS
• Figures IIA and IIB are schematic representations of an optoelectronic device and the first, second and third sensitivity of an optical sensor according to another embodiment.
• identical or identically acting components may each be provided with the same reference numerals.
• the illustrated elements and their proportions with each other are basically not to be regarded as true to scale, but individual elements, such as layers, components, components and areas, for better representability and / or better understanding exaggerated thick or large dimensions.
• V ⁇ curve 990 is shown for a wavelength range of 400 to 700 nanometers.
• the average spectral sensitivity R of the human eye is given on the y-axis in arbitrary units. If, in the following exemplary embodiments, wavelength-dependent slopes of the V ⁇ curve are specified and / or compared with wavelength-dependent slopes of the first and second sensitivity, it is assumed, unless explicitly stated otherwise, that the respective spectral dependencies are normalized to a maximum value of 1 are. This means that information about wavelength-dependent slopes of the V ⁇ curve is set to 1 refer to normalized V ⁇ curve whose maximum at about 555 nanometers has a spectral sensitivity R of 1. For the normalized V ⁇ curve of this type, the mean wavelength-dependent slope in the wavelength range between 600 and 650 nanometers is approximately -1% / nm.
• first semiconductor light sources 1 are described with at least one first LED 11, which awakens a cold white to yellowish green light impression.
• the at least one first LED 11 has, purely by way of example, an InGaN-based blue emitting epitaxial layer sequence on which a yellow-green-emitting wavelength conversion substance is applied.
• the color locus is approximately at x coordinates in the range of 0.36 to 0.37 and y coordinates in the range of 0.42 to 0.44, the characteristic first wavelength of the first LED 11 at approximately 565 nanometers.
• Semiconductor light sources 2 formed with at least one second LED 21 which emits light in a second, orange-red to red wavelength range around a second characteristic wavelength of about 610 nanometers around.
• LEDs usually also red wavelength conversion substances in conjunction with a blue emitting
• Wavelength range are in which the eye sensitivity is very low, so, as can be seen from the V ⁇ curve 990 in Figure IA, in a range of greater than or equal to about 640th Nanometers. Therefore, no additional red-emitting wavelength conversion substance is used for the exemplary embodiments described below for optoelectronic devices. Rather, the light having the second wavelength range is generated by the material of the epitaxial layer sequence of the at least one second LED 21 based on InGaAlP without the use of an additional red-emitting wavelength conversion substance.
• the second wavelength range can be better selected in the well-detectable red wavelength range below 640 nanometers.
• a high efficiency of more than 100 lumens / watt with a simultaneously high color rendering value of more than 90 can be achieved by the combinations of the white emitting first semiconductor light sources 1 and red emitting second semiconductor light sources 2 shown.
• Combinations of first and second semiconductor light sources with emission spectra in other first and second wavelength ranges can be used if a different color and light impression of the mixed light is desired. All conceivable optoelectronic devices according to the present description is the principle described here of the regulation and stabilization of the color locus of the radiated mixed light, which is generated by at least a first and a second semiconductor light source.
• the exemplary embodiments described below can generally have at least one first and one second semiconductor light source for so-called multi-color systems, which allow a good controllability of the white point to increase the quality of white light, such as optoelectronic devices which produce a mixed light with at least one first and a second or even more
• FIG. 1B shows a CIE standard color chart known to the person skilled in the art with the chromaticity coordinate x on the horizontal axis and the chromaticity coordinate y on the vertical axis.
• line 900 identifies the so-called white curve known to the person skilled in the art of a planck blackbody radiator at different temperatures. These temperatures are also referred to as color temperature.
• the color loci 901 for the first LED 11 described above are marked with the emission spectrum in the greenish-white first wavelength range for different ambient temperatures from 0 ° C. to 50 ° C.
• the color change is indicated for increasing ambient temperatures between 0 0 C and 50 0 C.
• the color loci 902 in the same temperature range from 0 0 C to 50 0 C drawn, which is also indicated here the color change in temperature with increasing ambient temperatures by the associated arrow.
• the change of the first and second characteristic wavelength ⁇ of the first and second wavelength ranges is further shown in FIG. 3B in nanometers for the first LED 11 through curve 941 and for the second LED 21 through the curve 942 as a function of the ambient temperature T in degrees Celsius.
• the second characteristic wavelength of the second, red-emitting LED 21 shifts toward greater wavelengths ⁇ for increasing ambient temperatures and at the same time loses the emitted light by about 40% in intensity.
• the first characteristic wavelength of the first LED 11 shifts to slightly shorter wavelengths, because the wavelength conversion substance of the first LED 11 becomes inefficient at higher temperatures. As a result, less converted light can be emitted from the first LED, resulting in a bluish color impression due to the fact that the proportion of converted light decreases.
• the radiated first intensity of the first LED 11 decreases by less than 20%. In the illustrated embodiment, therefore, the first LED 11 turns out in the Compared to the second LED 21 as a temperature stable and has a lower first temperature dependence of the first characteristic wavelength and the first intensity compared to the second temperature dependence of the second characteristic wavelength and the second intensity.
• FIG. 2 shows a section of the CIE standard color chart from FIG. 1B in the area of the chromaticity coordinate x between 0.40 and 0.48 and in the area of the chromaticity coordinate y between 0.37 and 0.43, in which the temperature dependence of the color loci 903 of FIG unregulated mixed light is more clearly visible.
• the following exemplary embodiments are based on the consideration that by controlling the ratio of the first intensity of the first LED 11 to the second intensity of the second LED 21, where the same temperatures for all LEDs are assumed here and below, because of the respective temperature dependence of the Although first and second characteristic wavelengths can not be controlled to a single color locus 903.
• the first and second semiconductor light sources 1, 2 are subject to the same temperature fluctuations and more preferably have the same operating temperature
• the temperature dependency of the color loci 903 may be minimized if, for example, the color locus shift along the connection line 920 between the color locus 921 at an ambient temperature of 0 0 C and the color locus 922 at an ambient temperature of 50 0 C causes.
• the connecting line 920 is chosen such that it lies perpendicular to the lines 911 and 921 and therefore, purely mathematically, means a minimum color locus shift. Furthermore, the connecting line 920 extends along the major axis of the MacAdams ellipse, which lies around the center 923 of the connecting line 920. Some MacAdams ellipses increased by about ten times are indicated in the CIE standard color chart in Figure IC for clarity. By controlling along the major axis of a MacAdams ellipse, as in the In general, the perceptibility of the color locus change of the color loci 903 of the mixed light are further minimized.
• the connecting line 920 shown in FIG. 2 is shown purely by way of example.
• connection lines between a first point on the line 911 and a second point on the line 912 are conceivable in order to achieve desired chromaticity dependencies of the mixed light by a corresponding control and compensation of the temperature-dependent change of the first and second intensity.
• FIG. 4A a schematic representation of an optoelectronic device 100 according to an exemplary embodiment is shown, which has a first semiconductor light source 1 with a first LED 11 described above and a second semiconductor light source 2 with a second LED 21 described above.
• the first and second semiconductor light source 1, 2 in the embodiment shown each have exactly one first or exactly one second
• the first and / or the second semiconductor light source 1, 2 may also comprise a plurality of first and second LEDs 11, 21.
• a first current 41 is applied to the first semiconductor light source 1 and a second current 42 is applied to the second semiconductor light source 2.
• the optoelectronic device 100 further has an optical sensor 3, onto which a part 110 of the light emitted by the first semiconductor light source 1 and a part 210 of the light emitted by the second semiconductor light source 2 are irradiated.
• the optical sensor 3 has a first wavelength-dependent sensitivity in the first wavelength range and a second wavelength-dependent sensitivity in the second wavelength range.
• the parts 110, 210 of the light of the first and second semiconductor light sources 1, 2 are converted by the optical sensor 3 into a first and a second sensor signal 341, 342.
• the respective signal strength depends on the first and second wavelength-dependent sensitivity of the wavelength ranges or the characteristic wavelengths and the intensities of the parts 110, 210 of the
• the mean color location of the mixed light can be set under preselected operating conditions.
• the mean color location can additionally be preselected by a suitable number of first LEDs 11 in the first semiconductor light source 1 and / or by a suitable number of second LEDs 21 in the second semiconductor light source 2.
• the optoelectronic device 100 has a control device 4 which regulates the first and second currents 41, 42 such that the ratio of the first sensor signal 341 to the second sensor signal 342 has a predetermined ratio and remains constant, for example.
• control device 4 analog and / or digital passive and active electronic components and circuits, which may be formed, for example, in one or more integrated circuits.
• control circuits for example, according to the principle of proportional regulators (P controller), for example, with additional integrating control (PI controller) and / or differential control (PD control, PID control) work, are known in the art and will not explained here.
• P controller proportional regulators
• PI controller additional integrating control
• Semiconductor light source 1, 2 and the first and second currents 41, 42 directly for the first and second semiconductor light source 1, 2 provide.
• FIG. 4B shows a part of the optoelectronic device according to the previous exemplary embodiment.
• the first semiconductor light source 1, the second semiconductor light source 2 and the optical sensor 3 are arranged in a housing 8, which is designed purely by way of example as a surface-mountable housing.
• the housing 8 comprises a plastic, such as epoxy and / or silicone, and can be prepared for example by means of a molding process as described in the general part.
• the housing 8 has a lead frame 81 for electrical connection or for contacting the first and second semiconductor light source 1, 2 and the optical sensor 3.
• the lead frame 81 is formed by the plastic material of the housing 8 and has a suitable one
• Terminal topography to allow the contacting of the arranged in the housing 8 components (not shown).
• the first and second semiconductor light sources 1, 2 and the optical sensor 3 are arranged in a recess 82 of the housing 8. Furthermore, in the recess 82, for example, a transparent plastic encapsulation for protecting the semiconductor light sources 1, 2 and the optical sensor 3 may be arranged (not shown). Alternatively, the semiconductor light sources 1, 2 and the optical sensor 3 can be mounted on the lead frame 81 and subsequently formed with the plastic material of the housing 8, wherein the housing 8 can then also be made transparent and without recess 82. In the arrangement shown, the parts 110, 210 of the light irradiated onto the optical sensor 3 by the first and second semiconductor light sources 1, 2 can each be part of the first and second LEDs 11, 21, ie parallel to the mounting plane , emitted light.
• the first and second semiconductor light sources 1 and 2 are in thermal contact through the housing 8 and the lead frame 81.
• the housing 8 and in particular the lead frame 81 act as a heat sink, which allow a uniform temperature distribution of the semiconductor light sources 1 and 2. This makes it possible to minimize self-heating effects in the semiconductor light sources 1 and 2 and to suspend the semiconductor light sources 1 and 2 as possible to the same temperatures and temperature changes allow reproducible behavior of the optoelectronic device 100.
• the arrangement of the first and second semiconductor light source 1, 2 and the optical sensor 3 in the housing 8 has an extremely compact construction.
• the control device 4 can be arranged in a further housing or in the form of an integrated circuit in the housing 8.
• the control device 4 for example, together with the lead frame 8 with the housing material to be transformed.
• the optical sensor 3 of the optoelectronic device 100 comprises a silicon photodiode 30, as shown in detail in FIGS. 5A and 5B in two exemplary embodiments, with electrical connections, for example, not being shown for the sake of clarity .
• the first and second sensitivity of the optical sensor 3 are adapted to the first and second temperature dependence of the first and second semiconductor light sources 1, 2 according to the above statements. This can be done by a suitable choice of the sensor material of the photodiode 30 itself.
• the optical sensor 3 has an optical filter 31 which has a transmission for light in the first and second wavelength range, which together with the intrinsic sensitivity of the photodiode 30, the desired first and second wavelength-dependent Sensitivity yields.
• the parts 110, 210 of the light irradiated by the first or second semiconductor light source 1, 2 over a large area onto the optical sensor 3 are converted by the photodiode 30 into an electrical signal.
• the first and second sensor signals 341, 342 are amplitude-modulated at two different frequencies by switching the currents on and off.
• the control device 4 has suitable frequency mixing and filtering circuits for demodulation, which are known to the person skilled in the art and will not be described further here.
• the optical sensor 3 can also have a first sensor facet 32 and a second sensor facet 33, which are optically and electrically separated from one another.
• the electrical isolation can be done for example by a photodiode array or a patterned photodiode 30 with separate active areas 301 and 302.
• the optical separation takes place in the exemplary embodiment shown by an optical filter 31, which has a light-permeable region 311 in the first wavelength range and a light-permeable region 312 in the second wavelength range.
• Wavelength range and the portion 210 of the light with the second wavelength range are discriminated by the optical filter 31 against each other and the first and second Sensor facets 32, 33 may provide the first and second sensor signals 341, 342 separately.
• the following figures show the control behavior of the optoelectronic device 100 for various examples and embodiments of optical sensors 3 having different first and second wavelength-dependent sensitivities.
• the temperature-dependent color location changes of the mixed light emitted by the optoelectronic device 100 were dependent on the
• FIGS. 6A and 6B the control behavior of the optoelectronic device is shown using optical sensors 3, each of which is designed as commercially available silicon photodiodes (available, for example, from Hamamatsu Photonics KK).
• the color locus change control response 961 is shown using a broadband photodiode having an intrinsic sensitivity that increases continuously from about 300 nanometers to about 1000 nanometers, then rapidly decays for wavelengths greater than about 1000 nanometers to about 1100 nanometers .
• FIG. 6B shows the control behavior in the form of the color locus change 962 when using a so-called VIS photodiode, which uses a Sensitivity maximum at about 550 nanometers, which drops rapidly on the shortwave side to about 300 nanometers and on the long wavelength side to about 800 nanometers.
• VIS photodiode uses a Sensitivity maximum at about 550 nanometers, which drops rapidly on the shortwave side to about 300 nanometers and on the long wavelength side to about 800 nanometers.
• the sensitivity in curve 971 is shown for an optical sensor 3 according to Figure 5A, which is implemented as a so-called ambient light detector (ALD) and which simulates the wavelength-dependent sensitivity of the human eye
• the sensitivity or sensitivity curve 971 thus corresponds to the V ⁇ curve 990 of Figure IA
• the optical sensor 3 a suitable optical filter 31, which in combination with the intrinsic sensitivity of
• Silicon photodiode 30 has the sensitivity 971 shown in Figure 7A.
• the sensitivity curve 972 shows the corresponding sensitivity of the second sensor facet 33 of FIG alternative optical sensor 3 according to FIG. 5B using an optical filter 31 with a suitable region 312.
• FIG. 7B as in FIGS. 6A and 6B, FIG.
• FIG. 8A shows a modified sensitivity compared to the V ⁇ curve 990
• this has a second sensitivity with a wavelength-dependent slope that is different from the wavelength-dependent slope of the V ⁇ curve 990 in the second wavelength range ,
• the sensitivity curve 981 falls on the long wavelength side slower than the V ⁇ curve 990 such that the ratio of the average wavelength dependent slope of the second sensitivity to the mean wavelength dependent slope of the V ⁇ curve 990 in the second wavelength range of about 600 to 650 nanometers is less than one.
• Sensitivity curve 982 again shows the second sensitivity of a second sensor facet 33 for an optical sensor 3 according to FIG. 5B.
• FIG. 8B shows the regulation behavior of the optoelectronic device 100 in the form of the temperature-dependent change of the color loci 983 of the emitted mixed light using such optical sensors 3.
• the color loci 983 have an average color locus for an average temperature and lie for the changing temperatures along the main axis of FIG MacAdams ellipse associated with the middle color location.
• Semiconductor light source 1, 2 is possible, so that the desired minimum temperature-dependent color locus shift of the mixed light emitted by the optoelectronic device is achieved.
• FIGS. 9A to 1OB show simulations for the control behavior of optoelectronic devices 100 in the form of temperature-dependent color position shifts of the emitted mixed light, the optoelectronic devices 100 having optical sensors 3 with different first and second sensitivities.
• the wavelength-dependent sensitivities 991, 992 and 993 in FIG. 9A have a maximum sensitivity of 1 at 570 nanometers, while the wavelength-dependent sensitivities 1001, 1002 and 1003 in FIG. 10A have a maximum sensitivity of 1 at 600 nanometers. For all shown sensitivities respectively
• Sensitivity curves increase the sensitivity of the associated simulated optical sensor 3 from 400 nanometers to the maximum linearly.
• the sensitivities 991, 992 and 993 in FIG. 9A and the sensitivities 1001, 1002 and 1003 in FIG. 2 have the slopes-2% / nm , -1% / nm and -0.5% / nm.
• the gradients are normalized as a percentage to the maximum value here and defined below. The abovementioned gradients thus also correspond to the respective wavelength-dependent slope of the second wavelength-dependent sensitivity of the optical sensor 3 in the second wavelength range.
• FIGS. 9B and 10B The temperature-dependent color position shifts of the mixed light emitted by the simulated optoelectronic devices resulting from the sensitivities shown are shown in FIGS. 9B and 10B, where the color locations 994 (triangles) the sensitivity 991 and the color loci 995 (non-filled circles) the sensitivity in FIGS 992 and 996 (squares) 993 based on the sensitivity.
• the color loci 1004 (triangles) have the sensitivity 1001, the color loci 1005 (non-filled circles), the sensitivity 1002 and the color loci 1006 (Squares) based on 1003 sensitivity.
• the spectral dependencies which comprise the respective second sensitivities in the second wavelength range, are likewise to be regarded as normalized to the maximum value of 1 in each case. Since the detailed profile below a wavelength of about 600 nanometers may have a smaller influence on the control behavior, the spectra could also be normalized to their value at a wavelength of 600 nanometers to 1, in which case the slopes mentioned with a factor of 2.5 to multiply.
• FIG. 11A shows an optoelectronic device 200 according to a further exemplary embodiment, which is a modification of the optoelectronic device 100 according to FIG. 4A.
• the optoelectronic device 200 additionally has a third semiconductor light source 5 with at least one third LED 51.
• the at least one third LED 51 and thus the third semiconductor light source 5 emit light with a third characteristic wavelength in a third, blue wavelength range and with a third intensity. Because of that, the third
• Wavelength range is different from the first and second wavelength range, in the optoelectronic device 200, the previously described temperature-dependent color change of location of the mixed light emitted by the optoelectronic device can be controlled and stabilized to a color location.
• the third characteristic wavelength and the third intensity have a third temperature dependence and / or current dependence and / or aging, to which a third sensitivity of the optoelectronic sensor 3 is adapted.
• the first, second and third sensitivities 1101, 1102 and 1103 of the optical sensor 3 and, for comparison, the V ⁇ curve 990 are shown in FIG. IIB.
• the optical sensor 3 converts a part 510 of the light emitted from the third semiconductor light source 5 into a third sensor signal 343.
• the control device 4 regulates the first, second and third currents 41, 42, 43 such that the ratio of two of the first, second and third sensor signals 341, 342, 343 each corresponds to a predetermined one
• Ratio that is either constant or changes in a predetermined manner in response to the first and / or second and / or third sensor signal 341, 342, 343.
• the color location of the mixed light can be adjusted.
• the wavelength ranges described here and characteristic Wavelengths allows the opto-electronic device 200 to set the color locus to be controlled along the white curve of the CIE standard color chart.
• Temperature dependence of the semiconductor light sources 1, 2 and 5 are compensated, so that no temperature-dependent or age-dependent color locus shift of the radiated from the optoelectronic device 200 mixed light is more perceptible.
• Sensitivity of the optical sensor 3 of the optoelectronic devices 100 and 200 a suitable control behavior can be achieved in which by means of the sensor sensor 3 provided by the sensor signals and control to constant sensor signal ratios by controlling the first, second and optionally third current, a desired color stability of the mixed light optoelectronic device 100 or 200 can be reached. This is possible because, in the case of the optoelectronic devices 100 and 200 described here, not only the intensity changes but also the wavelength changes of the light emitted by the semiconductor light sources are converted directly into suitable sensor signals.
• the color location stabilization problem with changing spectral components of the sources may be due to adjusted spectral sensitivities in the respective ones Spectral range of the sources (eg by one or more sensor facets) on the rules, such as keeping constant, the sensor signal ratios can be reduced by controlling the source currents.

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